The independent TV network Iran International on Saturday said it had been forced on UK police advice to shut down its London studios, after a "significant escalation in state-backed threats from Iran".
"I cannot believe it has come to this," said the network's general manager, Mahmood Enayat, adding that 24-hour broadcasts were continuing from the station's offices in Washington.
"A foreign state has caused such a significant threat to the British public on British soil that we have to move," he said.
"Let's be clear this is not just a threat to our TV station but the British public at large. Even more this is an assault on the values of sovereignty, security and free speech that the UK has always held dear."
The decision was taken late on Friday, a source at the station said, following the arrest last weekend of an Austrian-Iranian man in the vicinity of the studios in Chiswick, west London.
Magomed-Husejn Dovtaev, 30, was charged on Monday "with collecting information of a kind likely to be useful to a person committing or preparing an act of terrorism", police said. He has pleaded not guilty, British newspaper The Guardian reported.
In November, police installed concrete barriers outside the studios, similar to those at key government buildings and tourist spots in the British capital, to prevent any attack by vehicle.
On Saturday, the police said that despite the man's arrest, "we still have serious concerns for the safety of people working at this company".
"This has led to us giving further advice and the company is now relocating," it said, adding that its advice was "exceptional" and not "given lightly".
"The situation that journalists face around the world and the fact that some journalists face such hostile intentions of foreign states whilst in the UK is a challenging reality that we are determined to confront."